JP2020008581A - Measuring device for spindle or rotary table - Google Patents

Abstract

To provide a measuring device for a spindle or a rotary table.SOLUTION: The measuring device for a spindle or a rotary table comprises: first and second position sensing elements; and a scale element. The scale element comprises first and second graduations, and is arranged rotatably about an axis of rotation relative to the position sensing elements. The first graduation comprises regular structures arranged in parallel next to one another along a first direction, the second graduation comprises regular structures which are arranged in parallel next to one another along a first direction, two first position sensing elements are offset from one another in a circumferential direction, the two first position sensing elements can scan the first graduation, and can determine the axial position of the scale elements arranged vertically relative to the rotary axial line. The two second position sensing elements are offset from one another in a circumferential direction, and can scan the second graduation, and can determine the axial position of the scale element.SELECTED DRAWING: Figure 2

Description

  The invention relates to a measuring device for measuring the position of a spindle or a rotary table according to claim 1, and to an assembly for a spindle or rotary table with a corresponding measuring device.

  Related spindles or rotary tables are frequently used in machine tools or multi-task machines. Spindles or motor spindles often hold rotating tools, for example milling cutters, in machine tools. The work piece is fixed to a rotary table and then, for example, cut. Furthermore, the rotary table is used in a measuring instrument, in which a workpiece mounted on the rotary table is measured. Such spindles or turntables often include an angle measuring device used to measure the rotational movement of the shaft. Angle measuring devices are used in particular in machine tools or measuring instruments for measuring rotary movement.

  There is an increasing demand for improving the performance of such a spindle or rotary table, particularly the accuracy during operation.

  Japanese Patent Application Publication No. 2010-217167 discloses a measuring device having an encoder that generates a signal that enables measurement of a rotation speed of a shaft and infers an axial load of the shaft. ing.

Japanese Patent Application Publication No. 2010-217167

  It is an object of the present invention to provide a measuring device which is suitable for a spindle or a rotary table and makes it possible to determine the position of the rotation axis in several directions in an operating mode.

  According to the invention, this task is solved by the features of claim 1.

  Thus, the measuring device is suitable for a spindle or a rotary table and comprises at least two first position sensors, at least two second position sensors and a scale element, wherein the scale element is in the first section or It has a first scale and a second section or second scale. The scale element is rotatably positioned about the axis of rotation with respect to the first and second position sensors. The first section includes a regular pattern arranged in alignment with each other along a first direction parallel to each other, the first direction having a circumferential directional component. The second section includes a regular pattern arranged in alignment along a second direction parallel to one another, the second direction having an axial directional component. The at least two first position sensors are circumferentially offset from one another, the first section being scannable by the at least two first position sensors and oriented perpendicular to the axis of rotation. The position of the scale element in the plane (and thus the position of the axis of rotation or the axial displacement under load during operation) can be determined. Further, by scanning the first section with the at least one first position sensor, the angular position of the scale element relative to the first position sensor can be absolutely determined within one revolution. The at least two second position sensors are likewise arranged offset from one another in the circumferential direction, the second position sensor being able to scan the second section and the axial position of the scale element (and thus during operation, The axial displacement in the axial direction when a load is applied can be determined.

  By means of the at least one first position sensor, the angular position of the scale element with respect to the first position sensor can be determined absolutely within one revolution. This means, for example, that the first section has an absolute code track or that a reference mark is attached to the scale element, this reference mark being associated with the incremental section within one revolution. This can be achieved by the fact that it allows an absolute determination of the angular position.

  The first direction in which the regular patterns of the first section are arranged in alignment with each other may be the same as the circumferential direction. Similarly, the first direction with respect to the circumferential direction may be inclined or arranged obliquely (but not perpendicularly to the circumferential direction). Similarly, the second direction in which the regular patterns of the second section are arranged in alignment with one another may be arranged identically to the axial direction (and thus parallel to the axis of rotation). Similarly, the second direction may be inclined or oblique to the axial direction (but not perpendicular to the axial direction). For example, the regular pattern of the first section and the regular pattern of the second section may be oriented as arrows with respect to each other.

  Advantageously, the measuring device has at least three first position sensors and at least three second position sensors.

  In another embodiment of the invention, the measuring device has a printed wiring board on which at least one electronic component is mounted. In this case, the first position sensor is electrically connected to the electronic component, and the signal of the first position sensor can be processed by the electronic component. Alternatively or additionally, the second position sensor is electrically connected to the electronic component, and the signal of the second position sensor can be processed by the electronic component. In particular, processors or microcontrollers are considered as electronic components.

Advantageously, the printed wiring board has an annular shape. “Annular” can be understood as a closed ring shape, in which case the annular printed wiring board is configured as a closed ring extending over 360 °. The concept of “annular” can also be understood as an open ring shape, for example an open ring segment extending over at least 180 °, in particular at least 270 °.

  Advantageously, the first position sensor and the second position sensor are electrically connected to the electronic component, and the angular position of the scale element, the position of the scale element in a plane perpendicular to the axis of rotation, and the scale The axial position of the element can be determined by the electronic component.

  In another embodiment of the invention, the inclination of the scale element, and thus the rotation axis, can be determined by the second position sensor. In particular, at least the second position sensor may be electrically connected to the electronic component, with which the inclination of the scale element can be determined. It is particularly advantageous if more than two second position sensors are used.

  Of course, with a suitably rigid spindle or rotary table, such an inclination is relatively small, with an angle of less than 1 minute relative to the ideal axis of rotation, for example an angle of 100 to 50 seconds. Range. Therefore, even with these tilts, only minimal changes in position occur, and the measuring device has a very high resolution and can provide reliable information or quantitative values on the tilt. . Due to the rotation of the axis of rotation as required, said tilt may lead to oscillations of the scale element, such oscillations being quantified by the measuring device, especially by adding the measured angular positions. It can be kept in place.

  In another embodiment of the present invention, another sensor is mounted on the printed wiring board, which can measure acceleration or vibration, or temperature. In particular, two or more further sensors may be mounted on the printed wiring board.

  Advantageously, the memory chip, which can be used as a data logger for storing information based on signals generated by the first position sensor and / or the second position sensor and / or a further sensor, comprises: Attached to the board.

  Advantageously, the first position sensor and / or the second position sensor and / or the further sensor are connected to the annular printed circuit board by a flexible printed circuit board.

  In another embodiment of the present invention, the first position sensor and / or the second position sensor is configured as a magnetic sensor, and the pattern of the first section and / or the second section is configured as a magnetic pole. I have. The first position sensor and / or the second position sensor can operate, for example, on the principle of magnetoresistance or may be configured as a Hall sensor. Alternatively, the measuring device may be based on optical or inductive measuring principles, and it is also possible to combine these principles and thus scan the first section according to a different principle than the second section You can also.

  Advantageously, the sensor of the first position sensor capable of scanning the first section is offset with respect to the sensor of the second position sensor capable of scanning the second section in the axial direction. ing.

  Advantageously, at least the second compartment (or both compartments) is mounted on the circumference of the cylindrical scale element.

  As scale element, for example, an annular body that can be fixed to a shaft is considered. However, alternatively, the first and / or second compartment may be directly attached to the shaft.

  The invention comprises an assembly for a spindle or a rotary table with a measuring device, which assembly comprises a printed wiring board on which the electronic components are mounted, and thus the signals of the first and / or second position sensors are converted to electronic components. The assembly includes a casing, and the printed wiring board is surrounded by the casing.

  Advantageously, the assembly comprises a shaft, a biasing element and two bearings configured as rolling bearings. The scale element is displaceably mounted with respect to the shaft, and the bearing is axially biased by the biasing element such that the scale element is in the path of the axial biasing force. Alternatively or additionally, the measuring device comprises a measuring device casing axially displaceable with respect to the shaft, the bearings being arranged such that the measuring device casing is located in the path of the axial biasing force. , And is biased in the axial direction by the biasing member.

  Advantageous embodiments of the invention are described in the dependent claims.

  The measuring device detects, for example, the axis displacement of the tool spindle online, measures the rotor temperature in a non-contact manner, records the imbalance and vibration of the rotating axis, and relates to the operating conditions (maximum temperature, maximum vibration, operating time, etc.) The information can be stored for a longer period and output again. In particular, the target position can be corrected in a machining process or a measurement process by numerical control based on the measured value (axial displacement) of the angular position and position of the scale element on a plane perpendicular to the rotation axis. Thus, for example, the trajectory of a cutting tool clamped in a spindle can be corrected when machining a workpiece. In particular, the measuring device can be configured such that, in connection with the numerical control, a correction value is generated based on the position data measured by the measuring device in relation to the absolute angular position.

  For this purpose, the measuring device can advantageously have a resolution of less than 2 μm, in particular less than 1 μm, in particular less than 750 nm. These resolution values are obtained when determining both the axial position and the lateral position, i.e. the position in a plane perpendicular to the axis of rotation.

  Further details and advantages of the measuring device according to the invention will become clear from the following description of embodiments with reference to the accompanying drawings.

FIG. 3 is a longitudinal sectional view of a spindle provided with a measuring device. FIG. 2 is a cross-sectional view of a spindle provided with a measuring device. It is a detailed longitudinal section of a measuring device. FIG. 3 is a detailed view of a scale element of the measuring device.

  FIG. 1 shows a longitudinal section through a spindle of a machine tool, which in the illustrated embodiment is configured as a milling machine. The spindle comprises a first group of components 1 which may also be referred to as a "stator" and a second group of components which are rotatable about the axis of rotation A with respect to the first group of components 1 and are thus configured as rotors. And the constituent element group 2. Furthermore, the spindle is provided with two bearings 3, 4 configured here as rolling bearings, in particular as angular contact ball bearings. The second component group 2 of the spindle is driven by a motor (not shown).

  The first component group 1 has a casing 1.20, in which the bearings 3, 4 and the measuring device 12 are accommodated. In the casing 1.20, a measuring device casing 1.8 is provided. Are combined. Between the outer rings of the bearings 3, 4, a spacer sleeve 1.10. Is furthermore arranged axially.

  The second component group 2 comprises a shaft 2.2 on which the scale element 2.1 of the measuring device 12, the inner rings of the bearings 3, 4, the spacer ring 2.3 and the spacer sleeve 2.4 are arranged. Having. In the embodiment shown, a tool holder 2.5, here a hollow shaft cone, is fixed to one end of the shaft 2.2. A milling tool 2.6 is mounted on the tool holder 2.5.

  First, the measuring device 12 will be described with reference to FIGS. FIG. 2 shows a cross section of the measuring device 12 at the level of a plane P through the spindle, inside which a shaft 2.2 can be seen, with a scale element 2.1 on the shaft 2.2. Are displaceable in the axial direction, but are fixed so as not to rotate. The shaft 2.2 and the scale element 2.1 are arranged rotatably with respect to the printed circuit board 1.7 and in FIG. 2 are cast in FIG. 1 and FIG. 3 for clarity. Material 1.9 is not shown. The measuring device 12 comprises three first position sensors 1.1, 1.3, 1.5 and three second position sensors 1.2, 1.4, 1.6. The first position sensors 1.1, 1.3, 1.5 are arranged to be shifted from each other in the circumferential direction u. Similarly, the second position sensors 1.2, 1.4, 1.6 are arranged so as to be shifted from each other in the circumferential direction u.

  The position sensors 1.1 to 1.6 and the annular printed circuit board 1.7 are non-rotatably connected to the measuring device housing 1.8 and therefore non-rotatably to the spindle housing 1.20. ing. The printed circuit board 1.7 has, among other things, a first electronic component 1.71, a second electronic component 1.72, another sensor 1.73, and a memory chip 1.74.

  By means of a biasing element 2.21 (here a shaft nut), a mechanical biasing force can be introduced into the bearings 3, 4 of the spindle. In the presented embodiment, the measuring device comprises an annular scale element 2.1 displaceable with respect to the shaft 2.2 and an annular measuring device casing 1 displaceable with respect to the shaft 2.2 of the measuring device 12. .8 are located in the path of the axial biasing force.

  With reference to FIG. 3, the configuration of the position sensors 1.1 to 1.6 will be described with reference to the position sensors 1.1 assigned to the first position sensors 1.1, 1.3, 1.5. In the exemplary embodiment presented, all position sensors 1.1 to 1.6 are configured essentially identically, each with the same electrical contact with the printed circuit board 1.7. I have. Here, the position sensors 1.1 to 1.6 are configured as magnetic pickups. The position sensor 1.1 includes a sensor 1.11 and a substrate 1.12 disposed radially outward with respect to the sensor 1.11. The board 1.12 is electrically connected to the annular printed wiring board 1.7 by a flexible printed wiring board 1.13. In the exemplary embodiment presented, the sensor 1.11 is configured as a magneto-resistive detector. In particular, the sensor 1.11 can be configured as a magneto-resistive pattern on a glass substrate and can be electrically connected to the substrate 1.12 by contact.

  In contrast, there is an air gap between the sensor 1.11 or the position sensors 1.1-1.6 and the scale element 2.1, which air gap in the presented embodiment is less than 200 μm. Has dimensions. The sensors of the first position sensors 1.1, 1.3, 1.5 are displaced in the axial direction z with respect to the sensors of the second position sensors 1.2, 1.4, 1.6. Have been.

  In the embodiment shown, the scale element 2.1 is formed as a cylindrical or annular body, on the periphery of which both the first section 2.11 and the second section 2.12 are arranged. , The first section 2.11 is offset from the second section 2.12 in the axial direction z.

  FIG. 4 shows a cross-sectional view of the scale element 2.1 as viewed from the peripheral surface side. The first section 2.11 comprises regular patterns or lines (black and white rectangles in the figure) aligned parallel to each other along a first direction, the first direction being the direction of the circumferential direction u. With components. In the illustrated embodiment, the first direction is the same as the circumferential direction u. Further, the first section 2.11 includes a fiducial mark 2.111.

  The second section 2.12 includes regular patterns or lines (black and white rectangles in the figure) arranged in alignment along a second direction parallel to each other, the second direction being the axial direction With components. In the illustrated embodiment, the second direction is the same as the axial direction z.

  In other words, the first section 2.11 contains regular patterns, which are, in principle, configured here as rectangular, with the long sides of the rectangle oriented in the second direction. , Are arranged in parallel with each other. In the illustrated embodiment, the second direction is parallel to the rotation axis A or parallel to the direction z. The second section 2.12 also contains regular patterns, which are here arranged in a ring, the long sides of which are oriented in a first direction, They are arranged parallel to each other. The first direction extends in the circumferential direction u.

  The pattern of the illustrated embodiment is configured as a north pole and a south pole.

  The first section 2.11 can be scanned by the first position sensors 1.1, 1.3, 1.5, and the first section 2.11 can be scanned by the first position sensors 1.1, 1.3, 1.5. The angular position of the scale element 2.1 with respect to one position sensor 1.1, 1.3, 1.5 can be determined. The angular position can be determined absolutely within one revolution. For this purpose, as shown in FIG. 3, an incremental first section 2.11 can be used, which gives the absolute angular position over one revolution in relation to the reference mark 2.111. Alternatively, the first section 2.11 may be configured absolutely, for example, as a pseudo-random code or a Gray code in the sense of coding, and thus by generating a unique code value. The signals of the first position sensors 1.1, 1.3, 1.5 are transmitted to the electronic component 1.71, and the electronic components 1.71 have the first position sensors 1.1, 1.3, 1, 1 . 5 are electrically connected via conductor tracks of the printed wiring board 1.7. Next, a digital value of the angular position, in particular, is generated by the electronic component 1.71. Furthermore, by appropriately combining the position signals of the first position sensors 1.1, 1.3, 1.5 in the electronic component 1.71, the plane P in a plane P oriented perpendicular to the axis of rotation A The position of the scale element 2.1, ie the x, y coordinates of the actual position of the axis of rotation A, is determined. This position, which can also be referred to as the "lateral position", depends on the load applied to the milling tool 2.6 during machining for a given spindle. Furthermore, the absolute angular position of the shaft 2.2 is assigned to the actual lateral position, for example which cutting edge of the rice cutting tool 2.6 engages the workpiece and what load is applied to the spindle or shaft. 2.2 can be detected.

  Similarly, the second position sensors 1.2, 1.4, 1.6 are electrically connected to the electronic component 1.71. The second position sensors 1.2, 1.4, 1.6 are used to scan the second section 2.12, and are scanned by the second position sensors 1.2, 1.4, 1.6. The axial position of the scale element 2.1 can be determined. In the electronic component 1.71, the absolute angular position of the shaft 2.2 is also assigned to the position in the axial direction.

  According to the invention, it is possible to measure the lateral and axial position of the spindle or rotary table, especially as a function of the absolute angular position of the shaft 2.2, at the spindle or rotary table. Since the spindle or the rotary table is in any case designed very robustly, here a position measurement which varies in the range of μm or less is performed. Similarly, the inclination of the rotation axis A with respect to the casing 1.1 can be measured. For this purpose, in particular, a high resolution of the second position sensors 1.2, 1.4, 1.6 is required.

  During operation of the measuring device 12, the data from the further sensor 1.73 is stored in a memory chip 1.74 in the sense of a data logger and is stored, for example, so as to be able to track the temperature or impact load generated.

1 First Component Group 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 Position Sensor 1.11 Sensor 1.12 Board 1.13 Printed Wiring Board 1.7 Print Wiring board 1.71 First electronic component 1.72 Second electronic component 1.73 Separate sensor 1.74 Memory chip 1.8 Measuring device casing 1.9 Casting material 1.10 Spacer sleeve 1.20 Casing 2 Second component group 2.1 Scale element 2.11 First section 2.11 Fiducial mark 2.12 Second section 2.2 Shaft 2.21 Biasing element 2.3 Spacer ring 2.4 Spacer sleeve 2.5 Tool holder 2.6 Milling tool 3, 4 Bearing 12 Measuring device u Week direction z Axial direction A Rotation axis P Plane

Claims (15)

A measuring device (12) for a spindle or a rotary table,
At least two first position sensors (1.1, 1.3, 1.5), at least two second position sensors (1.2, 1.4, 1.6) and a scale element (2 .. 1), wherein the scale element comprises a first section (2.11) and a second section (2.12), and the first and second position sensors about a rotation axis (A). (1.1 to 1.6) are rotatably arranged,
A first section (2.11) comprising a regular pattern arranged in alignment with each other along a first direction parallel to each other, the first direction having a directional component in a circumferential direction (u); ,
A second section (2.12) comprises a regular pattern arranged in alignment with each other along a second direction parallel to each other, wherein the second direction has an axial component (z). And
At least two first position sensors (1.1, 1.3, 1.5) are arranged offset from one another in the circumferential direction (u), and at least two first position sensors (1.1, 1) are arranged. .3, 1.5), the first section (2.11) can be scanned and the scale element (2.1) in a plane (P) oriented perpendicular to the axis of rotation (A). The position is determinable, and is at least one first position sensor (1.1, 1.3, 1.5) and a value for the first position sensor (1.1, 1.3, 1.5). The angular position of the scale element (2.1) in the rotation is absolutely determinable;
At least two second position sensors (1.2, 1.4, 1.6) are arranged offset from one another in the circumferential direction (u) and the second position sensors (1.2, 1.4). , 1.6), the second section (1.2) can be scanned and the axial position of the scale element (2.1) can be determined, the measuring device (12) for a spindle or rotary table. ). The measuring device (12) according to claim 1,
The measuring device (12) comprises at least three first position sensors (1.1, 1.3, 1.5) and at least three second position sensors (1.2, 1.4, 1.... (12). The measuring device (12) according to claim 1 or 2,
The measuring device (12) has a printed wiring board (1.7) on which at least one electronic component (1.71, 1.72) is mounted, and a first position sensor (1.1, 1....). 3, 1.5) and / or a second position sensor (1.2, 1.4, 1.6) is electrically connected to the electronic component (1.71, 1.72), Signals of the position sensors (1.1, 1.3, 1.5) and / or the second position sensors (1.2, 1.4, 1.6) of the electronic component (1.71, 1.. A measuring device (12) processable by 72). The measuring device (12) according to claim 3,
A measuring device (12), wherein the printed wiring board (1.7) has an annular shape. The measuring device (12) according to claim 3 or 4,
The first position sensor (1.1, 1.3, 1.5) and the second position sensor (1.2, 1.4, 1.6) are used for the electronic component (1.71, 1.72). The electronic component (1.71, 1.72) can determine the angular position, the position in the plane (P), and the axial position of the scale element (2.1) by the electronic component (1.71, 1.72). A measuring device (12). The measuring device (12) according to any one of claims 1 to 5,
A measuring device (12) wherein the inclination of the scale element (2.1) and the rotation axis (A) can be determined by a second position sensor (1.1, 1.3, 1.5). The measuring device (12) according to any one of claims 3 to 6,
A measuring device (12) in which another sensor (1.73) is attached to the printed wiring board (1.7), and the acceleration or the temperature can be measured by the sensor. The measuring device (12) according to any one of claims 3 to 7,
A memory chip (1.74) is attached to the printed wiring board (1.7), and the memory chip is connected to the first position sensor (1.1, 1.3, 1.5) and / or the second position sensor. Measuring device usable as a data logger for storing information based on signals generated by a position sensor (1.2, 1.4, 1.6) and / or another sensor (1.73) (12). The measuring device (12) according to any one of claims 3 to 8,
The first position sensor (1.1, 1.3, 1.5) and / or the second position sensor (1.2, 1.4, 1.6) and / or the another sensor (1 .73) is connected to the annular printed circuit board (1.7) by a flexible printed circuit board (1.13). A measuring device (12) according to any one of the preceding claims,
The first position sensor (1.1, 1.3, 1.5) and / or the second position sensor (1.2, 1.4, 1.6) are configured as magnetic sensors; A measuring device (12), wherein the pattern of the first section (2.11) and / or the second section (2.12) is configured as a magnetic pole. The measuring device (12) according to any one of the preceding claims,
The sensor (1.11) of the first position sensor (1.1, 1.3, 1.5) replaces the sensor (1.2, 1.4, 1.6) of the second position sensor. A measuring device (12) which is offset relative to the axial direction (z). A measuring device (12) according to any one of the preceding claims,
A measuring device (12) in which a second section (2.12) is mounted on the circumference of a cylindrical scale element (2.1). In an assembly for a spindle or rotary table,
4. An assembly, comprising the measuring device (12) according to claim 3, wherein the assembly comprises a casing (1.20) and the printed wiring board (1.7) is surrounded by the casing (1.20). The assembly according to claim 12, wherein
Said assembly comprises a shaft (2.2), a biasing element (2.21) and two bearings (3, 4) configured as rolling bearings, said scale element (2.1) comprising a shaft (2.1). 2.2) axially displaceably mounted with respect to 2.2), wherein the bearings (3, 4) are biased in such a way that said scale element (2.1) is positioned in the path of the axial biasing force. An assembly biased axially by (2.21). The assembly according to claim 13 or 14,
The assembly comprises a shaft (2.2), a biasing element (2.21) and two bearings (3, 4) configured as rolling bearings, the measuring device (12) comprising a shaft (2.2). ) Comprising a measuring device casing (1.8) mounted axially displaceable with respect to the bearing, wherein the bearings (3, 4) are positioned such that the measuring device casing (1.8) is in the path of the axial biasing force. Assembly biased in the axial direction by a biasing member (2.21).

Images